Field of Invention
The present invention relates to an event detection method for waking up a portable electronic device and an action sensor using same; particularly, it relates to such event detection method and action sensor capable of accurately detecting a wake-up event when the portable electronic device is in a sleep mode.
Description of Related Art
Please refer to FIG. 1A and FIG. 1B, which show how the prior art switches a portable electronic device from a sleep mode to a normal operation mode and its drawback. When a portable electronic device is power ON but has not been in use for a certain period of time, typically, its power management system will shut down the operations of at least some of its components to reduce power consumption, which is the “sleep mode”. In the “normal operation mode” the portable electronic device operates normally, i.e., all the components of the portable electronic device are in operation or ready for operation. In the “sleep mode”, one or more of the components of the portable electronic device are not fully functioning such that the power consumption is reduced.
Conventionally, in a portable electronic device having an action sensor such as a capacitive touch sensor, an acceleration sensor, a gyro-sensor or the like, the action sensor is shut down in the sleep mode to reduce power consumption. Referring to FIG. 1A, in the normal operation mode, the action sensor senses action events with a data sensing frequency CLK1 (e.g., 100 Hz). During this normal operation mode, the action sensor is supplied with a current In (referring to as “normal current” hereinafter) which is sufficient for the action sensor to fully function, so as to sense action events with the best accuracy and resolution. When the portable electronic device enters into the sleep mode, the action sensor is shut down. However, a user may cause a certain wake-up event to happen, such as tapping a screen of the portable electronic device, in order to wake up the portable electronic device to resume it from the sleep mode to the normal operation mode. Therefore, although the action sensor is shut down, it should not be completely disabled, and typically in the prior art, the action sensor still senses action events but with a greatly reduced data sensing frequency. For example, referring to FIG. 1A, in the sleep mode, the action sensor detects whether there is a wake-up event with a much lower data sensing frequency CLK0 (typically about 1/100 of the data sensing frequency CLK1, e.g., 1 Hz). When a wake-up event is detected under this much lower data sensing frequency CLK0, the portable electronic device is resumed from the sleep mode to the normal operation mode.
Referring to FIG. 1B, the drawback of the prior art is that there is high possibility that the action sensor can not capture a wake-up event during the sleep mode. Typically, a user's tapping action is in a frequency range of about 10 Hz. With the low data sensing frequency CLK0, it is very likely that the action sensor will miss the tapping action, and as a result, the portable electronic device will not resume from the sleep mode to the normal operation mode.
In view of the above, to overcome the drawbacks in the prior art, the present invention proposes an event detection method for waking up a portable electronic device and an action sensor using the same, wherein such event detection method and action sensor are capable of accurately detecting a wake-up event when the portable electronic device is in a sleep mode.